Esters are known components for use in fragrance and flavouring applications. Esters of unsaturated acids have also found application as general chemicals, e.g. as solvents.
Alkanols can be used in the preparation of esters and in other chemical processes. The abstracts of JP 02 164848 A and JP 58021630 A disclose respectively the preparation of methacrylic esters by use of a blend of methyl methacrylate with a mixture of ethyl and butyl alcohols, and the purification of raw ethanol/butanol mixtures by the addition of ethyl acrylate. EP 499731 A1 documents the addition of alkanols to alkyl acrylate to form 3-alkyl propanoates. GB 1,174,148 relates to the production of esters of unsaturated acids, particularly acrylic and methacrylic esters via transesterification with alcohols and amino-alcohols. U.S. Pat. No. 5,606,102 concerns the purification of butyl acrylate from an azeotropic mixture of the acrylate and the esterifying alcohol, butanol.
Unsaturated esters have previously been used in diesel fuel applications; in particular, when the unsaturated esters are in the form of, or contained within, fatty acid methyl ester (FAME) compositions.
Low carbon number acrylates and methacrylates, for example methyl, ethyl and tert-butyl acrylates and methacrylates, are known to be skin sensitisers, where even a small amount, eg 0.1 wt %, can trigger a problem. Therefore it is undesirable to use such compounds as a component of a fuel composition.
EP 1731589 A2 discloses palm-based biodiesel formulations with enhanced cold flow properties. Alkyl esters of C6-C18 saturated or unsaturated fatty acids are disclosed as one possible component of the biodiesel.
US 2002/0026744 A1 discloses motor fuel compositions comprising an oxygen-containing component and optionally a hydrocarbon component. The oxygen-containing component disclosed therein comprises a mixture of organic compounds having oxygen-containing functional groups. The oxygen-containing functional groups disclosed therein include alcohols, ethers, aldehydes, ketones, esters, inorganic acid esters, acetals, epoxides and peroxides. The motor fuel compositions of US 2002/0026744 A1 were used as a fuel for various diesel, jet, gas-turbine and turbojet engines.
Esters as a general class of compounds alongside ethers, alcohols, ketones and other oxygenated components, are also proposed as additives for fuels in US 2001/0024966 A1, to improve vapour pressure properties. US 2001/0024966 A1 however does not specifically disclose or exemplify the use of low carbon number alkyl alkenoate compounds; the preferred use is of C5-C8 alkyl esters of saturated carboxylic acids.
FR 2757539 A1 discloses a fuel and a process for manufacturing a fuel from vegetable matter. The process disclosed involves the production of esters from vegetable matter, and the inclusion of them in a fuel.
Due to environmental concerns, there is a growing demand for the use of bio-components, i.e. components derived from a biological source, in gasoline.
Ethanol is a well known bio-component currently used in gasoline, however, it has been observed that the addition of ethanol to base gasoline has the effect of increasing the E70 and E100 of the formulated gasoline relative to the base gasoline. Therefore, in order to include significant quantities of ethanol in gasoline, the base gasoline to which it is added has to be specially formulated in order for the formulated gasoline to meet gasoline specifications around the world.